Official meteorological observations from London stations confirmed a minimum temperature of 14°C on September 1, locking in the market outcome with full certainty. This value fits within the typical early-September climatological range for the region, where overnight lows commonly fall between 12–16°C under settled high-pressure patterns and moderate Atlantic airflow. Post-event verification by agencies such as the Met Office removes forecast-model uncertainty and leaves only the recorded data as the resolution criterion. The sole realistic challenges would involve rare post-publication revisions to station data or debates over which specific site defines “London,” though such adjustments almost never alter the reported minimum after initial release.